In heretofore bidirectional, torque-limiting, brake spring clutch mechanism, as is exemplified in the U.S. Pat. No. 3,329,242 to Minarick et al and U.S. Pat. No. 3,659,682, to Meyer et al the driving torque is undesirably transmitted from the input drive shaft through the interference fit between the helical spring and an output shaft or drum of the clutch mechanism. In addition, since torque-limiting is achieved in such heretofore known torque-limiting, brake spring clutch mechanism by interrupting the interference fit of the helical spring, the torque-limiting load value as a function of spring force, is determined at the time of manufacture of the mechanism and is not thereafter readily adjustable in the field. Accordingly, the present invention contemplates a bidirectional, torque-limiting drive and brake mechanism or relatively simple and compact construction which does not have the aforesaid disadvantages of heretofore known spring clutch mechanisms of the bidirectional torque limiting and brake type.
Accordingly, an object of this invention is to provide a bidirectional, torque-limiting, drive and brake mechanism in which a driving torque is transmitted by a direct mechanical interconnection of driving parts and is not dependent upon an interference spring fit. Another object of the present invention is to provide a bidirectional, torque-limiting, drive and brake mechanism in which the torque-limiting load value is readily adjustable in the field after manufacture. A still further object of this invention is to provide a bidirectional, torque-limiting, drive and brake mechanism wherein the spring only functions as a brake and thus has a longer operative life than heretofore known spring clutch mechanisms of the same type.